Britannica Sources used in this answer

How does abetalipoproteinemia interfere with fat absorption and vitamin E levels?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

A composite diagram shows the structural formulas, space-filling models, and simplified depictions of lipid molecules including stearic acid and phosphatidylcholine, and how these assemble into a micelle and lipid bilayer, with labels identifying hydrophilic heads and hydrophobic tails. — Lipid Structure and properties of two representative lipids. Both stearic acid (a fatty acid) and phosphatidylcholine (a phospholipid) are composed of chemical groups that form polar “heads” and nonpolar “tails.” The polar heads are hydrophilic, or soluble in water, whereas the nonpolar tails are hydrophobic, or insoluble in water. Lipid molecules of this composition spontaneously form aggregate structures such as micelles and lipid bilayers, with their hydrophilic ends oriented toward the watery medium and their hydrophobic ends shielded from the water.

Abetalipoproteinemia is an autosomal recessive condition caused by a deficiency of microsomal transfer protein. This protein is essential for the assembly and secretion of lipoproteins containing apolipoprotein B, such as chylomicrons and very-low-density lipoproteins (VLDL).12

Because these lipoproteins are required to transport dietary fats from the intestine into the bloodstream, their absence leads to severe fat malabsorption, causing triglycerides to accumulate within the gastrointestinal tract and liver.1

This defect also interferes with the transport of fat-soluble nutrients. Specifically, the inability to properly package and circulate these lipids results in very low blood levels of vitamin E. The resulting vitamin E deficiency is clinically significant, as it leads to serious neurological and physiological complications, including nerve damage, retinal defects, and an unsteady gait.1